1. Field of the Invention
The invention relates to circuit arrangements for testing switch or relay contacts and use for automatic firing arrangements.
2. Description of the Prior Art
Control or regulating units are employed in the control or regulating art for controlling or regulating processes. In order to switch such control or regulating units on or off, it is known to use switches or relays whose switching contacts or movable switching elements respectively assume in the rest condition a given position in which the so-called "rest contact" is contacted while in another switch condition they can be lifted off the rest contact and can be applied to another contact. For reasons related to safety procedure, it is important for reliable operation of the control device or the mode of operation controlled or in particular regulated thereby that testing of the contacts of the switches or relays is effected in order to ensure that the process is stopped or cannot in any way initially start in the event of a malfunction, in particular if in the rest condition it is not the rest contact but another contact of the switch that is contacted.